Sealed structure, light-emitting device, electronic device, and lighting device

ABSTRACT

A sealed structure with high sealing capability, in which a pair of substrates is attached to each other with a glass layer is provided. The sealed structure has a first and second substrates, a first surface of the first substrate facing a first surface of the second substrate, and the glass layer which is in contact with the first and second substrates, defines a space between the first and second substrates, and is provided along the periphery of the first surface of the first substrate. The first substrate has a corner portion. The area of the first surface of the first substrate is smaller than or equal to that of the first surface of the second substrate. In at least one of respective welded regions between the glass layer and the first or second substrate, the width of the corner portion is larger than that of the side portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sealed structure using a pair ofsubstrates and a glass layer. Further, the present invention relates toa light-emitting device, an electronic device, and a lighting deviceeach using organic electroluminescence (hereinafter also referred to asEL).

2. Description of the Related Art

In recent years, development of light-emitting devices and displaydevices has been actively promoted, and improvements in reliability andyield, and the like have been demanded.

A sealed structure with high sealing capability can be used suitably fora display device or a light-emitting device in which a display element,a light-emitting element, or the like is an object to be sealed.

For example, in a light-emitting device, an element whose propertiessuch as reliability are rapidly deteriorated by exposure to the aircontaining moisture or oxygen, such as a light-emitting element usingorganic electroluminescence (also referred to as an organic EL element),is preferably provided inside a sealed structure with high sealingcapability.

Patent Document 1 discloses an organic EL panel in which a substrate anda sealing substrate are attached to each other with an adhesive layer.

REFERENCE

-   Patent Document 1: Japanese Published Patent Application No.    2011-81944

SUMMARY OF THE INVENTION

Further, in fabricating or using a light-emitting device, force islikely to be more applied to a corner portion of the light-emittingdevice, and thus a pair of attached substrates of the light-emittingdevice tends to be detached from each other from the corner portion.

For example, a technique in which a plurality of light-emitting devices(or display devices) is formed in one substrate, a trench is formed(scribed) in a top surface of the one substrate and a top surface of theother substrate, and the substrates are cut along the trench is known.In cutting the substrates in the technique, force tends to beconcentrated on a corner portion of the light-emitting device, so thatthe pair of attached substrates tends to be detached from each other.

Therefore, it is requested that the adhesion between a substrate and anadhesive layer be as high as possible at a corner portion of a sealedstructure.

As an example of an adhesive for attaching the pair of substrates, resinsuch as a light curing resin or a heat curing resin is known. Uponattachment of the pair of substrates, the shape of the resin sandwichedby the pair of substrates is changed to, for example, increase its widthby crush. That is, the shape of the resin provided over one of thesubstrates is different between before and after the attachment.

For example, in the case where the application quantity of the resin islarge, the resin may spread out of its predetermined region onattachment to be mixed into a region where an object to be sealed isprovided, whereby the object is contaminated. To the contrary, too muchreduction in application quantity of the resin in order to suppress thespread out of its appropriate region may lead to a lack of sufficientresin in the predetermined region after the attachment (the objectcannot be sealed enough in some cases).

One object of one embodiment of the present invention is to provide asealed structure with high sealing capability.

Further, one object of one embodiment of the present invention is toprovide a highly reliable light-emitting device in which an organic ELelement is sealed by the sealed structure.

Still further, one object of one embodiment of the present invention isto provide a highly reliable electronic device or a highly reliablelighting device using the light-emitting device.

A sealed structure of one embodiment of the present invention has aspace surrounded by a pair of substrates and a glass layer, in which atleast one of the substrate has a corner portion, the glass layer isprovided along the periphery of the one substrate having a cornerportion, and in at least one of a region where the glass layer isattached to the one substrate and a region where the glass layer isattached to the other substrate (the region also referred to as a weldedregion between the glass layer and the substrate), the width of itscorner portion is larger than that of its side portion. Accordingly, thearea of at least the one welded region between the glass layer and theone substrate is large in a corner portion of the sealed structure, sothat the adhesion between the glass layer and the substrate in thecorner portion can be increased. Consequently, if force is concentratedon the corner portion of the sealed structure, detachment of the pair ofattached substrates from each other can be suppressed.

In this specification, the interval between an inner contour and anouter contour of the welded region between the glass layer and thesubstrate is referred to as the width of the welded region. In thisspecification, for example, the interval between the inner contour andthe outer contour in the corner portion (side portion) of the weldedregion is referred to as the width of the corner portion (side portion).Likewise, the interval between an inner contour and an outer contour ofthe glass layer is referred to as the width of the glass layer.

In the above-described embodiment of the present invention, the glasslayer is used to attach the pair of substrates. The sealing capabilityof glass is higher than that of resin, and thus glass is preferable. Inaddition, glass is less likely to be deformed on attachment, and thusthe shape of the glass layer after attachment can be predicted beforethe attachment, which enables suppression of generation of such a defectthat the glass layer does not exist in its predetermined region afterthe attachment and thus an object to be sealed cannot be sealed enough.Accordingly, a sealed structure with high sealing capability can bemanufactured at high yield. Further, the glass layer (or glass frit,frit paste, or the like for forming the glass layer) can be providedover the substrate, in its desired shape after attachment, which leadsto simplification of manufacturing of the sealed structure.

Specifically, one embodiment of the present invention is a sealedstructure including a first substrate and a second substrate, a firstsurface of the first substrate facing a first surface of the secondsubstrate, and a glass layer which is in contact with the firstsubstrate and the second substrate, defines a space between the firstsubstrate and the second substrate, and is provided along the peripheryof the first surface of the first substrate. The first substrate has acorner portion. The area of the first surface of the first substrate issmaller than or equal to that of the first surface of the secondsubstrate. In at least one of a welded region between the glass layerand the first substrate and a welded region between the glass layer andthe second substrate, the width of the corner portion is larger thanthat of the side portion.

The sealing capability of the sealed structure is high because the pairof substrates is attached with the glass layer. In addition, in thesealed structure, detachment of the pair of substrates attached with theglass layer from each other can be suppressed even if force isconcentrated on the corner portion because in the corner portion, thearea of the welded region between the glass layer and the substrate islarge and the adhesion between the glass layer and the substrate ishigh. Further, detachment of the pair of attached substrates from eachother can be suppressed even if force is concentrated on the cornerportion in the manufacturing process of the sealed structure, whichleads to an improvement in yield.

Note that the present invention encompasses not only a structure inwhich the substrate is in direct contact with the glass layer, but alsoa structure in which the substrate is in indirect contact with the glasslayer through a film provided over the substrate. In this specification,the welded region between the glass layer and the substrate may denote awelded region between the glass layer and the film provided over thesubstrate, depending on the structure.

According to one embodiment of the present invention, even in the casewhere the substrate is in indirect contact with the glass layer throughthe film provided over the substrate, the area of a welded regionbetween the film and the glass layer in a corner portion of the sealedstructure is large, whereby the adhesion between the film and the glasslayer in the corner portion can be improved. Accordingly, detachment ofthe pair of attached substrates from each other can be suppressed evenif force is concentrated on the corner portion of the sealed structure.

One embodiment of the present invention is a sealed structure includinga first substrate and a second substrate, a first surface of the firstsubstrate facing a first surface of the second substrate, and a glasslayer which is in contact with the first substrate and the secondsubstrate, defines a space between the first substrate and the secondsubstrate, and is provided along the periphery of the first surface ofthe first substrate. The first substrate has a corner portion. The areaof the first surface of the first substrate is smaller than or equal tothat of the first surface of the second substrate. In at least one of awelded region between the glass layer and the first substrate and awelded region between the glass layer and the second substrate, theradius of the outer contour is smaller than or equal to that of theinner contour in its corner portion.

In the sealed structure, in at least one of the welded region betweenthe glass layer and the first substrate and the welded region betweenthe glass layer and the second substrate, the corner portion of theouter contour and the corner portion of the inner contour eachindividually have a shape along a circle. In this specification, theradius of a circle along which the corner portion of the contour has theshape is referred to as the radius of the contour.

With the structure in which the radius of the outer contour is smallerthan or equal to that of the inner contour, the adhesion between theglass layer and the substrate in the corner portion of the sealedstructure can be improved because the area of the welded region betweenthe glass layer and the substrate is large in the corner portion.

One embodiment of the present invention is a light-emitting deviceincluding a first substrate and a second substrate, a first surface ofthe first substrate facing a first surface of the second substrate, anda glass layer which is in contact with the first substrate and thesecond substrate, defines a region for an object to be sealed betweenthe first substrate and the second substrate, and is provided along theperiphery of the first surface of the first substrate. The firstsubstrate has a corner portion. The area of the first surface of thefirst substrate is smaller than or equal to that of the first surface ofthe second substrate. The region for an object to be sealed includes alight-emitting element in which a layer containing a light-emittingorganic compound is provided between a pair of electrodes. In at leastone of a welded region between the glass layer and the first substrateand a welded region between the glass layer and the second substrate,the width of the corner portion is larger than that of the side portion.

In the above-described light-emitting device, the glass layer, which hasa high effect of sealing, is used as a sealant. Accordingly,deterioration of the light-emitting element (organic EL element)attributable to entry of an impurity such as moisture or oxygen from theoutside of the light-emitting device can be suppressed.

Further, since in at least one of the welded region between the glasslayer and the first substrate and the welded region between the glasslayer and the second substrate in the above-described light-emittingdevice, the width of the corner portion is larger than that of the sideportion, the area of the welded region between the glass layer and thesubstrate in a corner portion of the light-emitting device is large,whereby the adhesion between the glass layer and the substrate in thecorner portion can be improved. Accordingly, detachment of the pair ofattached substrates from each other can be suppressed even if force isconcentrated on the corner portion of the light-emitting device.Further, detachment of the pair of attached substrates from each othercan be suppressed even if force is concentrated on the corner portion inthe manufacturing process of the light-emitting device, which leads toan improvement in yield.

One embodiment of the present invention is a light-emitting deviceincluding a first substrate and a second substrate, a first surface ofthe first substrate facing a first surface of the second substrate, anda glass layer which is in contact with the first substrate and thesecond substrate, defines a region for an object to be sealed betweenthe first substrate and the second substrate, and is provided along theperiphery of the first surface of the first substrate. The firstsubstrate has a corner portion. The area of the first surface of thefirst substrate is smaller than or equal to that of the first surface ofthe second substrate. The region for an object to be sealed includes alight-emitting element in which a layer containing a light-emittingorganic compound is provided between a pair of electrodes. In at leastone of a welded region between the glass layer and the first substrateand a welded region between the glass layer and the second substrate,the radius of the outer contour is smaller than or equal to that of theinner contour in its corner portion.

In the light-emitting device, in at least one of the welded regionbetween the glass layer and the first substrate and the welded regionbetween the glass layer and the second substrate, the corner portion ofthe outer contour and the corner portion of the inner contour eachindividually have a shape along a circle. With the structure in whichthe radius of the outer contour is smaller than or equal to that of theinner contour, the adhesion between the glass layer and the substrate inthe corner portion of the light-emitting device can be improved becausethe area of the welded region between the glass layer and the substrateis large in the corner portion.

One embodiment of the present invention is an electronic device usingthe light-emitting device. One embodiment of the present invention is alighting device using the light-emitting device. Application of thelight-emitting device whose pair of substrates attached is less likelyto be detached from each other even if force is concentrated on itscorner portion owing to its high adhesion between the substrate and theglass layer in the corner portion enables a highly reliable electronicdevice or a highly reliable lighting device to be achieved.

According to one embodiment of the present invention, a sealed structurewith high sealing capability can be provided.

Further, a highly reliable light-emitting device in which an organic ELelement is sealed by the sealed structure can be provided.

Still further, a highly reliable electronic device or a highly reliablelighting device using the light-emitting device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A1 to 1A3 and FIGS. 1B1 to 1B3 illustrate a sealed structure ofone embodiment of the present invention and a sealed structure of acomparison example, respectively;

FIGS. 2A to 2E illustrate sealed structures of embodiments of thepresent invention;

FIGS. 3A and 3B illustrate a light-emitting device of one embodiment ofthe present invention;

FIGS. 4A and 4B illustrate a light-emitting device of one embodiment ofthe present invention;

FIGS. 5A and 5B illustrate a light-emitting device of one embodiment ofthe present invention;

FIGS. 6A to 6C illustrate EL layers;

FIGS. 7A to 7E illustrate electronic devices and a lighting device ofembodiments of the present invention;

FIG. 8 illustrates lighting devices of embodiments of the presentinvention;

FIGS. 9A to 9C illustrate an electronic device of one embodiment of thepresent invention;

FIGS. 10A to 10C illustrate a method for manufacturing a sealedstructure of one embodiment of the present invention in Example 1;

FIGS. 11A and 11B show results of Example 1; and

FIGS. 12A and 12B show results of Example 1.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention are described in detail using thedrawings. The present invention is not limited to the followingdescription, and it will be easily understood by those skilled in theart that various changes and modifications can be made without departingfrom the spirit and scope of the present invention. Therefore, thepresent invention should not be construed as being limited to thedescription in the following embodiments. In the structures of thepresent invention described below, the same portions or portions havingsimilar functions are denoted by the same reference numerals in thedrawings, and description of the portions is not repeated.

(Embodiment 1 )

In this embodiment, a sealed structure of one embodiment of the presentinvention is described using FIGS. 1A1 to 1A3, FIGS. 1B1 to 1B3, andFIGS. 2A to 2E.

A sealed structure of one embodiment of the present invention includes afirst substrate and a second substrate, a first surface of the firstsubstrate facing a first surface of the second substrate, and a glasslayer which is provided along the periphery of the first surface of thefirst substrate. The first substrate has a corner portion. The area ofthe first surface of the first substrate is smaller than or equal tothat of the first surface of the second substrate. The first substrateis attached to the second substrate with the glass layer. In at leastone of a welded region between the glass layer and the first substrateand a welded region between the glass layer and the second substrate,the width of the corner portion is larger than that of the side portion.

The sealing capability of the sealed structure is high because the pairof substrates is attached with the glass layer. In addition, theadhesion between the glass layer and the substrate is high in the cornerportion because the area of the welded region between the glass layerand the substrate is large in the corner portion. Thus, detachment ofthe pair of attached substrates from each other can be suppressed evenif force is concentrated on the corner portion of the sealed structure.Further, detachment of the pair of attached substrates from each othercan be suppressed even if force is concentrated on the corner portion inthe manufacturing process of the sealed structure, which leads to animprovement in yield.

In the case where resin is used to attach a pair of substrates, theshape of the resin sandwiched by the pair of substrates is changed to,for example, increase the width by crush.

For example, in the case where the application quantity of the resin islarge, the resin may spread out of its predetermined region onattachment to be mixed into a region where an object to be sealed,whereby the structure is contaminated. To the contrary, too muchreduction in application quantity of the resin in order to suppress thespread out of its appropriate region may lead to a lack of sufficientresin in the predetermined region after the attachment (the structurecannot be sealed enough in some cases).

In the above-described embodiment of the present invention, the glasslayer is used to attach the pair of substrates. The sealing capabilityof glass is higher than that of resin, and thus glass is preferable. Inaddition, glass is less likely to be deformed on attachment, and thusthe shape of the glass layer after attachment can be predicted beforethe attachment, which enables suppression of generation of such a defectthat the glass layer does not exist in its predetermined region afterthe attachment and thus an object to be sealed cannot be sealed enough.Accordingly, a sealed structure with high sealing capability can bemanufactured at high yield. Further, the glass layer (or glass frit,frit paste, or the like for forming the glass layer) can be providedover the substrate, in its desired shape after attachment, which leadsto simplification of manufacturing of the sealed structure.

In this embodiment, for ease of description, it is supposed that theshape of the glass layer in its formed state over the one substrate isthe same as that of the welded region between the glass layer and thesubstrate (and/or the counter substrate) in the state after attachment.

A plan view of a sealed structure of one embodiment of the presentinvention is shown in FIG. 1A1. An enlarged view of a region surroundedby a dotted line 111 in FIG. 1A1 is shown in FIGS. 1A2 and 1A3.

In the sealed structure of the embodiment of the present invention shownin FIGS. 1A1 to 1A3, a glass layer 105 a is provided over a quadrangularsubstrate 101 along the periphery of the substrate 101. Then, thesubstrate 101 is attached to a counter substrate with the glass layer105 a, so that a space 102 surrounded by the pair of substrates and theglass layer 105 a is provided.

In this embodiment, a surface of the substrate and a surface of thecounter substrate, which face each other, have the same area. Forexample, in the plan view of the sealed structure shown in FIG. 1A1, theshape of the counter substrate is the same as that of the substrate 101.

An object to be sealed is included in the space 102. There is noparticular limitation on the object to be sealed; for example, anorganic EL element, an element included in a plasma display, a liquidcrystal element, and the like can be given. A transistor or a colorfilter may also be provided.

A plan view of a sealed structure of a comparative example is shown inFIG. 1B1. An enlarged view of a region surrounded by a dotted line 112in FIG. 1B1 is shown in FIGS. 1B2 and 1B3.

In the sealed structure of the comparative example shown in FIGS. 1B1 to1B3, a glass layer 105 b is provided over a quadrangular substrate 101along the periphery of the substrate 101. Then, the substrate 101 isattached to a counter substrate with the glass layer 105 b, so that aspace 102 surrounded by the pair of substrates and the glass layer 105 bis provided.

A difference between the glass layer 105 a of the sealed structure ofone embodiment of the present invention and the glass layer 105 b of thesealed structure of the comparative example (which can also be conceivedas a difference between a welded region between the glass layer 105 aand the substrate 101 and a welded region between the glass layer 105 band the substrate 101) is described below.

As shown in FIG. 1A2, as for the glass layer 105 a, a width of thecorner portion, W1 is larger than that of the side portion, W2.

On the other hand, as shown in FIG. 1B2, as for the glass layer 105 b, awidth of the side portion, W4 is equal to that of the corner portion,W3.

In this specification, the width of the side portion refers to the widthof a line which is perpendicular to the side. Further, the width of thecorner portion refers to the width of a line which connects anintersection in respective extensions of two sides of the outer contour,which do not face each other (see an intersection 15 in FIG. 1A2) to theinner contour by the most direct way.

It can be seen from FIGS. 1A2 and 1B2 that the area of the welded regionbetween the glass layer and the substrate in a corner portion of thesealed structure is larger in the sealed structure of the embodiment ofthe present invention in which the width of the corner portion is largerthan that of the side portion in a corner portion of the welded region,than in the sealed structure of the comparison example. Therefore,application of one embodiment of the present invention enables theadhesion between the glass layer and the substrate in the corner portionof the sealed structure to be improved.

Further, as shown in FIG. 1A3, in a corner portion of the glass layer105 a, a radius of the outer contour, R1 is smaller than a radius of theinner contour, R2.

On the other hand, as shown in FIG. 1B3, in a corner portion of theglass layer 105 b, a radius of the outer contour, R3 is larger than aradius of the inner contour, R4.

It can be seen from FIGS. 1A3 and 1B3 that the area of the welded regionbetween the glass layer and the substrate in the corner portion of thesealed structure is larger in the sealed structure of the embodiment ofthe present invention in which the radius of the outer contour issmaller than or equal to that of the inner contour in the corner portionof the welded region, than in the sealed structure of the comparisonexample. Therefore, application of one embodiment of the presentinvention enables the adhesion between the substrate and the glass layerin the corner portion of the sealed structure to be improved.

Further, it is preferable to decrease the radius of the outer contour inthe corner portion of the welded region between the glass layer and thesubstrate to as close to zero as possible, because the area of thewelded region in the corner portion of the sealed structure increasesaccordingly, and thus the adhesion between the glass layer and thesubstrate in the corner portion of the sealed structure furtherincreases.

Respective plan views of sealed structures of other embodiments of thepresent invention are shown in FIGS. 2A to 2E.

The width of a corner portion of a glass layer 105 c in a sealedstructure shown in FIG. 2A is larger than that of a side portion of thesame.

As shown in the glass layer 105 c shown in FIG. 2A, the outer contour ina corner portion of a welded region between the glass layer and thesubstrate may have an angle. In the case where the outer contour has, anangle, the angle is any of a right angle, an acute angle, and an obtuseangle.

The shape of the first surface of the substrate of the sealed structureof one embodiment of the present invention is not limited to quadrangle.As for the first substrate and the second substrate, the area of thefirst surface of the first substrate, which faces the first surface ofthe second substrate, is smaller than or equal to that of the firstsurface of the second substrate, and the first substrate has the cornerportion. For example, as described below, a substrate the shape of thefirst surface of which is hexagonal can be used in one embodiment of thepresent invention.

In a sealed structure shown in FIG. 2B, a glass layer 135 is providedover a substrate 131 the shape of the first surface of which ishexagonal, along the periphery of the substrate 131. Then, the substrate131 is attached to a counter substrate with the glass layer 135, so thata space 132 surrounded by the pair of substrates and the glass layer 135is provided.

As for the glass layer 135, the width of a corner portion is larger thanthat of a side portion. Further, in the corner portion of the glasslayer 135, the radius of the outer contour is smaller than that of theinner contour. Accordingly, the area of the welded region between theglass layer and the substrate in a corner portion of the sealedstructure shown in FIG. 2B is large, and thus the adhesion between theglass layer and the substrate in the corner portion can be improved.

In a corner portion of a sealed structure shown in FIG. 2C, a glasslayer 155 a is provided over a substrate 151. A width of a cornerportion of the glass layer 155 a, W5 is larger than that of a sideportion of the glass layer 155 a, W6.

Likewise, in a corner portion of a sealed structure shown in FIG. 2D, aglass layer 155 b is provided over a substrate 151. A width of a cornerportion of the glass layer 155 b, W7 is larger than that of a sideportion of the glass layer 155 b, W8.

Further, in a corner portion of a sealed structure shown in FIG. 2E, aglass layer 155 c is provided over a substrate 151. A width of a cornerportion of the glass layer 155 c, W9 is larger than that of a sideportion of the glass layer 155 c, W10.

Accordingly, in any of the sealed structures shown in FIGS. 2C to 2E,the welded area between the glass layer and the substrate in the cornerportion is large, so that the adhesion between the substrate and theglass layer in the corner portion can be improved.

In the case where the glass layer and the object to be sealed areprovided over the same substrate, the order of formation of the objectand the glass layer is not limited. The glass layer and the object maybe provided over different substrates. Formation of the glass layer mayinvolve a heat treatment; thus, it is preferable that the glass layerand the object be provided over different substrates in the case wherethe heat resistance of the object is low.

The glass layer can be formed of glass frit, for example. A glass ribboncan also be used. The glass frit or the glass ribbon contains at least aglass material.

The glass frit contains a glass material as a frit material; forexample, magnesium oxide, calcium oxide, strontium oxide, barium oxide,cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadiumoxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide,lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide,iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobiumoxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide,lithium oxide, antimony oxide, lead borate glass, tin phosphate glass,vanadate glass, or borosilicate glass is contained. The glass fitpreferably contains at least one or more kinds of transition metals toabsorb infrared light.

One example of a method for manufacturing a sealed structure of oneembodiment of the present invention is described below. In thisembodiment, the glass layer 105 a is formed of glass frit over thesubstrate 101 (see FIG. 1A1). Although the manufacturing process of anobject to be sealed is omitted below, the object to be sealed isprovided for the substrate 101 or the counter substrate.

First, frit paste is applied over the substrate 101 by a printing methodsuch as screen printing or gravure printing, a dispensing method, or thelike. In particular, use of the printing method such as screen printingor gravure printing is preferable because the frit paste can be formedeasily into a desired shape. The difference between the shape of theresulting glass layer and the shape of this frit paste is small, andtherefore the frit paste is preferably provided in its desired shapeafter attachment. In this embodiment, the frit paste is formed into ashape similar to that of the glass layer 105 a, over the substrate 101.

The frit paste contains the frit material and a resin (also referred toas a binder) diluted by an organic solvent. As for the frit paste, aknown material and a known composition can be used. For example,terpineol, n-butyl carbitol acetate, or the like can be used as theorganic solvent and a cellulosic resin such as ethylcellulose can beused as the resin. Further, an absorbent of light with a wavelength oflaser light may be contained in the frit paste.

Next, pre-baking is performed thereon to remove the resin or binder inthe frit paste, so that the glass layer is formed.

The top surface of the glass layer is preferably flat to increase theadhesion to the counter substrate. Thus, a planarization treatment suchas application of pressure may be performed thereon. The planarizationtreatment can be performed before or after the pre-baking.

Then, the substrate 101 and the counter substrate are disposed to faceeach other to make the glass layer and the counter substrate in closecontact with each other, and the glass layer is irradiated with thelaser light. For example, the beam diameter of the laser light ispreferably greater than the width of the side portion of the glass layer(specifically, for example, equal to the width of the corner portion ofthe same), because the structure of one embodiment of the presentinvention can be easily obtained.

Through the above, the sealed structure in which the substrate 101 andthe counter substrate are attached to each other with the glass layer105 a can be fabricated.

Further, for example, a defect portion where the glass layer does notexist in its predetermined region can be detected before attachment;thus, the substrate having this defect portion can be removed from themanufacturing process, thereby reducing execution of an unnecessarymanufacturing process; alternatively, frit paste may be further appliedover that substrate, and pre-baking may be performed thereon again,whereby the defect portion can be repaired. In this manner, according toone embodiment of the present invention, a reduction in yield can besuppressed by detecting a defect portion before attachment.

The sealing capability of the sealed structure of one embodiment of thepresent invention is high because the pair of substrates is attachedwith the glass layer as described above. In addition, the adhesionbetween the glass layer and the substrate is high in the corner portionbecause the area of the welded region between the glass layer and thesubstrate is large in the corner portion. Thus, detachment of the pairof attached substrates from each other can be suppressed even if forceis concentrated on the corner portion of the sealed structure. Further,detachment of the pair of attached substrates from each other can besuppressed even if force is concentrated on the corner portion in themanufacturing process of the sealed structure, which leads to animprovement in yield.

Further, the sealed structure of one embodiment of the present inventionis less likely to be deformed on attachment, and the shape of the glasslayer after attachment can be predicted before the attachment, whichenables the sealed structure to be manufactured at high yield. Further,the glass layer (or glass frit, frit paste, or the like for forming theglass layer) can be provided over the substrate, in its desired shapeafter the attachment, which leads to simplification of manufacturing ofthe sealed structure.

This embodiment can be combined with any other embodiment asappropriate.

(Embodiment 2)

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 3A and 3B.

FIG. 3A is a plan view of a light-emitting device of one embodiment ofthe present invention. FIG. 3B is a cross-sectional view taken alongdashed-dotted line A-B in FIG. 3A.

The light-emitting device shown in FIGS. 3A and 3B includes alight-emitting portion 802 provided in a space 810 surrounded by asupport substrate 801, a sealing substrate 806, and a glass layer 805.

A first surface of the support substrate 801 faces a first surface ofthe sealing substrate 806, and the glass layer 805 is provided along theperiphery of the first surface of the sealing substrate 806. The sealingsubstrate 806 has a corner portion at each of four corners of the firstsurface. The area of the first surface of the sealing substrate 806 issmaller than that of the first surface of the support substrate 801.

In each corner portion of the glass layer 805, the radius of the outercontour is smaller than that of the inner contour. Further, in the glasslayer 805, the width of the corner portion is larger than that of theside portion. In this embodiment, the shape of a welded region betweenthe glass layer 805 and the support substrate 801 and the shape of awelded region between the glass layer 805 and the sealing substrate 806are each the same as the top-surface shape of the glass layer 805 shownin FIG. 3A.

The light-emitting portion 802 includes a light-emitting element 130(including a first electrode 118, an EL layer 120, and a secondelectrode 122). A bank 124 covers an end portion of the first electrode118, and is provided with an opening in a position which overlaps with alight-emitting region of the light-emitting element 130.

The sealing capability of the light-emitting device is high because thelight-emitting element 130 is provided in the space 810 surrounded bythe pair of substrates and the glass layer 805. In addition, theadhesion between the substrate and the glass layer 805 in the cornerportion of the light-emitting device can be increased because the weldedarea between the substrate and the glass layer 805 is large in thecorner portion. Accordingly, detachment of the pair of attachedsubstrates from each other can be suppressed even if force isconcentrated on the corner portion of the light-emitting device.

For example, in the case where a plurality of light-emitting devices ismanufactured over the same substrate, a trench is formed (scribed) in atop surface of the substrate and/or a counter substrate, and thesubstrates are cut along the trench, force tends to be concentrated on acorner portion of the light-emitting device, so that the pair ofattached substrates tends to be detached from each other. However, inthe light-emitting device of one embodiment of the present invention,detachment of the pair of substrates attached with the glass layer fromeach other can be suppressed even if force is concentrated on the cornerportion of the light-emitting device, because the adhesion between thesubstrate and the glass layer in the corner portion is high.Accordingly, yield of the light-emitting device can be improved.

In the light-emitting device, the glass layer is used to attach the pairof substrates. The glass layer is less likely to be deformed onattachment, and thus the shape of the glass layer after attachment canbe predicted before the attachment, which enables suppression ofgeneration of such a defect that the glass layer does not exist in itspredetermined region after the attachment and thus an object to besealed cannot be sealed enough. Accordingly, a light-emitting devicewith high sealing capability can be manufactured at high yield. Further,the glass layer (or glass frit, frit paste, or the like for forming theglass layer) can be provided over the substrate, in its desired shapeafter attachment, which leads to simplification of manufacturing of thelight-emitting device.

In the light-emitting device shown in FIG. 3A, a space is formed betweenthe glass layer 805 and the light-emitting portion 802. A desiccant maybe contained in the space. There is a case where heat of the irradiationwith laser light leads to deterioration of an element or the like in thelight-emitting portion 802; thus, a material functioning as a heat sinkmay be contained in the space.

In the light-emitting device described in this embodiment, the glasslayer 805 is provided along the periphery of the sealing substrate 806.Therefore, the glass layer 805 is preferably formed over the sealingsubstrate 806 in its forming process. Further, the light-emittingelement 130 is provided over the support substrate 801 in thelight-emitting device described in this embodiment and there is a casewhere the light-emitting element 130 contains a material whose heatresistance is low. Therefore, also for suppressing deterioration of suchan element in the step of pre-baking of frit paste or the like, it ispreferable that the glass layer 805 be formed over the sealing substrate806 in its forming process.

The support substrate 801 and the sealing substrate 806 are in directcontact with the glass layer 805 in this embodiment. However,embodiments of the present invention are not limited thereto; one orboth of the substrates may be in indirect contact with the glass layer805 through a film provided therebetween. Since irradiation with laserlight is performed in the manufacturing process, the film providedbetween the substrate and the glass layer 805 is preferably formed usinga high heat-resistant material. For example, an inorganic insulatingfilm formed as a base film or an interlayer insulating film over thesubstrate may be in direct contact with the glass layer 805.

<Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention>

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As to theglass layer, refer to the above-described description.

[Support Substrate 801, Sealing Substrate 806]

As materials for the substrates, glass, quartz, a resin, or the like canbe used. Specifically, a material is used which has a heat resistancewhich is high enough to withstand the process temperature in themanufacturing process of the sealed structure, such as pre-baking orlaser light irradiation. For the substrate on the side from which lightfrom the light-emitting element is extracted, a material which transmitsthat light is used.

In order to suppress dispersion of an impurity included in the supportsubstrate 801 into any element provided over the support substrate 801,to provide an insulating layer on the top surface of the supportsubstrate 801 or to perform a heat treatment on the support substrate801 is preferable.

[Light-Emitting Element 130]

There is no limitation on the method for driving the light-emittingelement 130; either an active matrix method or a passive matrix methodcan be used. Further, any of a top emission structure, a bottom emissionstructure, and a dual emission structure can be used.

A light-emitting element with a bottom emission structure is used as anexample for description in this embodiment.

As examples of a light-transmitting material for the first electrode118, indium oxide, indium tin oxide (ITO), indium zinc oxide, zincoxide, zinc oxide to which gallium is added, and the like can be given.

Further, for the first electrode 118, a metal material such as gold,platinum, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, or titanium can also be used. A nitride of the metal material(e.g., titanium nitride) or the like may also be used. Graphene or thelike may also be used. In the case of using the metal material (or thenitride thereof), the first electrode is preferably formed to be thin soas to be able to transmit light.

The EL layer 120 includes at least a light-emitting layer. Thelight-emitting layer contains a light-emitting organic compound. The ELlayer 120 can have a stacked-layer structure, in which a layercontaining a substance having a high electron-transport property, alayer containing a substance having a high hole-transport property, alayer containing a substance having a high electron-injection property,a layer containing a substance having a high hole-injection property, alayer containing a bipolar substance (a substance having a highelectron-transport property and a high hole-transport property), and thelike are combined as appropriate to the above-described light-emittinglayer. Examples of the structure of the EL layer are described in detailin Embodiment 5.

The second electrode 122 is provided on the side opposite to the lightextraction side and is formed using a reflective material. As thereflective material, a metal material such as aluminum, gold, platinum,silver, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, orpalladium can be used. Any of the following can also be used: an alloycontaining aluminum (aluminum alloy) such as an alloy of aluminum andtitanium, an alloy of aluminum and nickel, and an alloy of aluminum andneodymium; and an alloy containing silver such as an alloy of silver andcopper. The alloy of silver and copper is preferable because of its highheat resistance. Lanthanum, neodymium, geimanium, or the like may beadded to the metal material or alloy.

[Bank 124]

As a material for the bank 124, a resin or an inorganic insulatingmaterial can be used. As the resin, for example, a polyimide resin, apolyamide resin, an acrylic resin, a siloxane resin, an epoxy resin, ora phenol resin can be used.

In particular, either a negative photosensitive resin or a positivephotosensitive resin is preferably used for easy formation of the bank124.

The bank 124 is provided so as to cover an end portion of the firstelectrode 118. The bank 124 is preferably formed to have a curvedsurface with curvature in its upper end portion or lower end portion inorder to improve the coverage with the EL layer 120 or the secondelectrode 122 which is formed over the bank 124.

There is no particular limitation to the method for forming the bank; aphotolithography method, a sputtering method, an evaporation method, adroplet discharging method (e.g., an inkjet method), a printing method(e.g., a screen printing method or an off-set printing method), or thelike may be used.

[Space 810]

The space 810 may be filled with an inert gas such as a rare gas or anitrogen gas or a solid such as an organic resin, or may be in a reducedpressure atmosphere. A dry agent may be provided in the space 810. Forthe thy agent, a substance which absorbs moisture and the like bychemical adsorption or a substance which adsorbs moisture and the likeby physical adsorption can be used. An oxide of an alkali metal, anoxide of an alkaline earth metal (e.g., calcium oxide or barium oxide),sulfate, a metal halide, perchlorate, zeolite, and silica gel can begiven as examples thereof.

This embodiment can be combined with any other embodiment asappropriate.

(Embodiment 3)

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 4A and 4B. FIG. 4A is a planview of a light-emitting device of one embodiment of the presentinvention. FIG. 4B is a cross-sectional view taken along dashed-dottedline C-D in FIG. 4A.

In a light-emitting device of this embodiment, a support substrate 801is attached to a sealing substrate 806 with a glass layer 805. A firstsurface of the support substrate 801 faces a first surface of thesealing substrate 806, and the glass layer 805 is provided along theperiphery of the first surface of the sealing substrate 806. The firstsurface of the sealing substrate 806 has a depression. The first surfaceof the sealing substrate 806 has a corner portion. The area of the firstsurface of the sealing substrate 806 is smaller than that of the firstsurface of the support substrate 801.

The width of a corner portion of the glass layer 805 is larger than thatof a side portion of the same. Further, in the corner portion of theglass layer 805, the outer contour has an angle, specifically, an obtuseangle. In this embodiment, the shape of a welded region between theglass layer 805 and the sealing substrate 806 is the same as the topsurface of the glass layer 805 shown in FIG. 4A.

In the light-emitting device of this embodiment, a light-emittingelement 130 (a first electrode 118, an EL layer 120, and a secondelectrode 122) is provided in a space 810 surrounded by the supportsubstrate 801, the sealing substrate 806, and the glass layer 805. Thelight-emitting element 130 has a bottom emission structure;specifically, the first electrode 118 is provided over the supportsubstrate 801, the EL layer 120 is provided over the first electrode118, and the second electrode 122 is provided over the EL layer 120.

The sealing capability of the light-emitting device is high because thelight-emitting element 130 is provide in the space 810 surrounded by thepair of substrates and the glass layer 805. In addition, the adhesionbetween the substrate and the glass layer 805 in a corner portion of thelight-emitting device can be increased because the welded area betweenthe substrate and the glass layer 805 is large in the corner portion.Accordingly, detachment of the pair of attached substrates from eachother can be suppressed even if force is concentrated on the cornerportion of the light-emitting device.

In the light-emitting device, the glass layer is used to attach the pairof substrates. The glass layer is less likely to be deformed onattachment, and thus the shape of the glass layer after attachment canbe predicted before the attachment, which enables suppression ofgeneration of such a defect that the glass layer does not exist in itspredetermined region after the attachment and thus an object to besealed cannot be sealed enough. Accordingly, a light-emitting devicewith high sealing capability can be manufactured at high yield. Further,the glass layer (or glass frit, frit paste, or the like for forming theglass layer) can be provided over the substrate, in its desired shapeafter attachment, which leads to simplification of manufacturing of thelight-emitting device.

A first terminal 809 a is electrically connected to an auxiliary wiring163 and the first electrode 118. An insulating layer 125 is provided ina region which overlaps with the auxiliary wiring 163 and the firstterminal 809 a over the first electrode 118. The first terminal 809 a iselectrically isolated from the second electrode 122 by the insulatinglayer 125. A second terminal 809 b is electrically connected to thesecond electrode 122. In this embodiment, the first electrode 118 isformed over the auxiliary wiring 163; however, the auxiliary wiring 163may be fawned over the first electrode 118.

The organic EL element emits light in a region with a refractive indexhigher than that of the air; thus, when light is extracted to the air,total reflection occurs in the organic EL element or at the interfacebetween the organic EL element and the air under a certain condition,which results in a light extraction efficiency of lower than 100%.

Specifically, supposing that the refractive index of a medium A ishigher than the refractive index of a medium B and the refractive indexof the medium B is lower than the refractive index of the EL layer, whenlight enters the medium B from the medium A, total reflection occurs insome cases depending on its incident angle.

In that case, it is preferable that an uneven surface structure beprovided at the interface between the medium A and the medium B. Withsuch a structure, such phenomenon that light entering the medium B fromthe medium A at an incidence angle exceeding a critical angle is totallyreflected and the wave of the light propagates inside the light-emittingdevice to lower the light extraction efficiency can be suppressed.

For example, an uneven surface structure 161 a is preferably provided inthe interface between the support substrate 801 and the air. Therefractive index of the support substrate 801 is higher than therefractive index of the air. Therefore, with the uneven surfacestructure 161 a provided in the interface between the air and thesupport substrate 801, light which cannot be extracted to the air owingto total reflection can be reduced, whereby the light extractionefficiency of the light-emitting device can be improved.

Further, an uneven surface structure 161 b is preferably provided in theinterface between the light-emitting element 130 and the supportsubstrate 801.

However, in the organic EL element, unevenness of the first electrode118 might lead to occurrence of leakage current in the EL layer 120formed over the first electrode 118. Therefore, in this embodiment, aplanarization layer 162 having a refractive index higher than or equalto that of the EL layer 120 is provided in contact, with the unevensurface structure 161 b. Accordingly, the first electrode 118 can beprovided to be a flat film, and thus occurrence of leakage current inthe EL layer due to the unevenness of the first electrode 118 can besuppressed. Further, owing to the uneven surface structure 161 b in theinterface between the planarization layer 162 and the support substrate801, light which cannot be extracted to the air due to total reflectioncan be reduced, whereby the light extraction efficiency of thelight-emitting device can be increased.

In FIG. 4B, the support substrate 801, the uneven surface structure 161a, and the uneven surface structure 161 b are different components;however, embodiments of the present invention are not limited thereto.Two or all of these may be formed as one component.

Although the light-emitting device shown in FIG. 4A is octagonal,embodiments of the present invention are not limited thereto. The shapeof the light-emitting device may be any other polygonal or a shapehaving a curved portion as long as it is a shape having a cornerportion. As the shape of the light-emitting device, a triangle, aquadrangle, a regular hexagon, or the like is particularly preferable.The reason for this is that a plurality of light-emitting devices can beprovided with a redundant space as little as possible in a limited area;a light-emitting device can be formed using a limited substrate areaefficiently. Further, the number of light-emitting elements in thelight-emitting device is not limited to one; a plurality oflight-emitting elements may be provided therein.

<Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention>

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As for thesubstrate, the light-emitting element, the sealant, and the space, theirrespective materials described above in the embodiments can be used.

[Insulating Layer 125]

The insulating layer 125 can be formed using a material similar to anyof the materials for the bank 124 described above in the embodiments.

[Auxiliary Wiring 163, First Terminal 809 a, and Second Terminal 809 b]

The auxiliary wiring 163, the first terminal 809 a, and the secondterminal 809 b are preferably formed by the same step(s) (at the sametime), because the number of manufacturing steps of the light-emittingdevice can be reduced. For example, they can be formed to have asingle-layer structure or a stacked-layered structure using a materialselected from copper (Cu), titanium (Ti), tantalum (Ta), tungsten (W),molybdenum (Mo), chromium (Cr), neodymium (Nd), scandium (Sc), andnickel (Ni) or an alloy material containing any of these materials asits main component.

[Uneven Surface Structure 161 a, 161 b]

The shape of the unevenness does not necessarily have an order ofregularity. When the shape of the unevenness is periodic, the unevennessfunctions as a diffraction grating depending on the size of theunevenness, so that an interference effect is increased and light with acertain wavelength is more likely to be extracted to the air. Therefore,it is preferable that the shape of the unevenness be not periodic.

There is no particular limitation on the shape of bottom surface of theunevenness; for example, the shape may be a polygon such a triangle or aquadrangle, a circle, or the like. When the shape of bottom surface ofthe unevenness has an order of regularity, the unevenness is preferablyprovided so that gaps are not formed between adjacent portions of theunevenness. A regular hexagon is given as an example of a preferableshape of the bottom surface.

There is no particular limitation on the cross-sectional shape of theunevenness in the direction perpendicular to the bottom surface; forexample, a hemisphere or a shape with a vertex such as a circular cone,a pyramid (e.g., a triangular pyramid or a square pyramid), or anumbrella shape can be used.

In particular, the size or the height of the unevenness is preferably 1μm or more, because influence of interference of light can besuppressed.

The uneven surface structure 161 a, 161 b can be provided directlyon/underneath the support substrate 801. As the method therefor, forexample, an etching method, a sand blasting method, a microblastprocessing method, a droplet discharge method, a printing method (screenprinting or offset printing by which a pattern is formed), a coatingmethod such as a spin coating method, a dipping method, a dispensermethod, an imprint method, a nanoimprint method, or the like can be usedas appropriate.

As the material of the uneven surface structure 161 a, 161 b, forexample, resin can be used; specifically, a polyester resin such aspolyethylene terephthalate (PET) or polyethylene naphthalate (PEN), apolyacrylonitrile resin, a polyimide resin, an acrylic(polymethylmethacrylate) resin, a polycarbonate (PC) resin, apolyethersulfone (PES) resin, a polyamide resin, a cyclic olefin-basedresin, a cycloolefin resin, a polystyrene resin, a polyamide imideresin, a polyvinylchloride resin, or the like can be used. A resin inwhich two or more kinds of the above resins are combined may be used. Itis preferable to use an acrylic resin because of its high visible lighttransmittance. A cyclic olefin-based resin and a cycloolefin resin areeach preferable because they have high visible light transmittance andhigh heat resistance.

For the uneven surface structure 161 a, 161 b, a hemispherical lens, amicro lens array, a film provided with an uneven surface structure, alight diffusing film, or the like can be used. For example, the lens orfilm can be attached over/below the support substrate 801 with anadhesive or the like with substantially the same refractive index as thelens or film, so that the uneven surface structure 161 a, 161 b can beformed.

[Planarization Layer 162]

The planarization layer 162 is more flat in its one surface which is incontact with the first electrode 118 than in its other surface which isin contact with the uneven surface structure 161 b. Therefore, the firstelectrode 118 can be formed to be flat. As a result, generation ofleakage current in the EL layer 120 due to unevenness of the firstelectrode 118 can be suppressed.

As a material of the planarization layer 162, liquid, resin, or the likehaving a high refractive index can be used. The planarization layer 162has a light-transmitting property. As examples of the resin having ahigh refractive index, resin containing bromine, resin containingsulfur, and the like are given; for example, a sulfur-containingpolyimide resin, an episulfide resin, a thiourethane resin, a brominatedaromatic resin, or the like can be used. Polyethylene terephthalate(PET), triacetyl cellulose (TAC), or the like can also be used. As theliquid having high refractive index, contact liquid (refractive liquid)containing sulfur and methylene iodide, or the like can be used. Any ofa variety of methods suitable for the material may be employed forforming the planarization layer 162. For example, the above resin isdeposited by a spin coating method and is cured by heat or light. Thematerial and the formation method can be selected as appropriate inconsideration of the adhesion strength, ease of processing, or the like.

This embodiment can be combined with any other embodiment asappropriate.

(Embodiment 4)

In this embodiment, a light-emitting device of one embodiment of thepresent invention is described using FIGS. 5A and 5B. FIG. 5A is a planview of a light-emitting device of one embodiment of the presentinvention and FIG. 5B is a cross-sectional view taken alongdashed-dotted line E-F in FIG. 5A.

An active matrix light-emitting device according to this embodimentincludes, over a support substrate 801, a light-emitting portion 802, adriver circuit portion 803 (gate side driver circuit portion), a drivercircuit portion 804 (source side drive circuit portion), and a glasslayer 805. The light-emitting portion 802 and the driver circuitportions 803 and 804 are sealed in a space 810 formed by the supportsubstrate 801, a sealing substrate 806, and the glass layer 805.

A first surface of the support substrate 801 faces a first surface ofthe sealing substrate 806, and the glass layer 805 is provided along theperiphery of the first surface of the sealing substrate 806. The firstsurface of the sealing substrate 806 has a corner portion. The area ofthe first surface of the sealing substrate 806 is smaller than that ofthe first surface of the support substrate 801.

In a corner portion of the glass layer 805, the radius of the outercontour is smaller than that of the inner contour. Further, the width ofthe corner portion of the glass layer 805 is larger than that of a sideportion of the same. In this embodiment, the shape of a welded regionbetween the glass layer 805 and the sealing substrate 806 is the same asthat of the top surface of the glass layer 805 shown in FIG. 5A.

The light-emitting portion 802 shown in FIG. 5B includes a plurality oflight-emitting units each including a switching transistor 140 a, acurrent control transistor 140 b, and a second electrode 122electrically connected to a wiring (a source electrode or a drainelectrode) of the transistor 140 b.

A light-emitting element 130 has a top emission structure, including afirst electrode 118, an EL layer 120, and the second electrode 122.Further, a bank 124 is formed to cover an end portion of the secondelectrode 122.

The sealing capability of the light-emitting device is high because thelight-emitting element 130 is provide in the space 810 surrounded by thepair of substrates and the glass layer 805. In addition, the adhesionbetween the substrate and the glass layer 805 in the corner portion ofthe light-emitting device can be increased because the welded areabetween the substrate and the glass layer 805 is large in the cornerportion. Accordingly, detachment of the pair of attached substrates fromeach other can be suppressed even if force is concentrated on the cornerportion of the light-emitting device.

Further, in the light-emitting device, the glass layer is used to attachthe pair of substrates. The glass layer is less likely to be deformed onattachment, and thus the shape of the glass layer after attachment canbe predicted before the attachment, which enables suppression ofgeneration of such a defect that the glass layer does not exist in itspredetermined region after the attachment and thus an object to besealed cannot be sealed enough. Accordingly, a light-emitting devicewith high sealing capability can be manufactured at high yield. Further,the glass layer (or glass frit, frit paste, or the like for forming theglass layer) can be provided over the substrate, in its desired shapeafter attachment, which leads to simplification of manufacturing of thelight-emitting device.

Over the support substrate 801, a lead wiring 809 for connecting anexternal input terminal through which a signal (e.g., a video signal, aclock signal, a start signal, or a reset signal) or a potential from theoutside is transmitted to the driver circuit portion 803, 804 isprovided. Here, an example thereof is described in which a flexibleprinted circuit (FPC) 808 is provided as the external input terminal. Aprinted wiring board (PWB) may be attached to the FPC 808. In thisspecification, the light-emitting device includes in its category notonly the light-emitting device itself but also the light-emitting deviceprovided with an FPC or a PWB.

The driver circuit portion 803, 804 includes a plurality of transistors.An example in which the driver circuit portion 803 includes a CMOScircuit which is a combination of an n-channel transistor 142 and ap-channel transistor 143 is shown in FIG. 5B. A circuit included in thedriver circuit portion can be formed using any type of circuit such as aCMOS circuit, a PMOS circuit, or an NMOS circuit. In this embodiment, adriver-integrated type in which a driver circuit and a light-emittingportion are formed over the same substrate is described; however,embodiments of the present invention are not limited to this structure,in which a driver circuit can be formed over a substrate that isdifferent from a substrate over which a light-emitting portion isformed.

To prevent increase in the number of manufacturing steps, the leadwiring 809 is preferably formed using the same material and the samestep(s) as those of the electrode or the wiring in the light-emittingportion or the driver circuit portion.

Described in this embodiment is an example in which the lead wiring 809is formed using the same material and the same step(s) as those of thegate electrode of the transistor included in the light-emitting portion802 and the driver circuit portion 803.

In FIG. 5B, the glass layer 805 is in contact with a first insulatinglayer 114 over the lead wiring 809. The adhesion of the glass layer 805to metal is low in some cases. Therefore, the glass layer 805 ispreferably in contact with an inorganic insulating film over the leadwiring 809; such a structure enables a light-emitting device with highsealing capability and high reliability to be achieved. As examples ofthe inorganic insulating film, an oxide film of a metal or asemiconductor, a nitride film of a metal or a semiconductor, and aoxynitride film of a metal or a semiconductor are given; specifically, asilicon oxide film, a silicon nitride film, a silicon oxynitride film, asilicon nitride oxide film, an aluminum oxide film, a titanium oxidefilm, and the like can be given.

<Materials that can be Used for Light-Emitting Device of One Embodimentof the Present Invention>

Examples of materials that can be used for the light-emitting device ofone embodiment of the present invention are described below. As for thesubstrate, the light-emitting element, the glass layer, the space, andthe bank, their respective materials described above in the embodimentscan be used.

[Transistor]

There is no particular limitation on the structure of the transistor(e.g., the transistor 140 a, 140 b, 142, or 143) used in thelight-emitting device of one embodiment of the present invention. Atop-gate transistor may be used, or a bottom-gate transistor such as aninverted staggered transistor may be used. A channel-etched type or achannel-stop (channel-protective) type may also be employed. Inaddition, there is no particular limitation on materials for thetransistor.

The gate electrode can be formed to have a single-layer structure or astacked-layer structure using any of metal materials such as molybdenum,titanium, chromium, tantalum, tungsten, aluminum, copper, neodymium, andscandium, or an alloy material which contains any of these elements, forexample. A structure may be employed in which a film of ahigh-melting-point metal such as titanium, molybdenum, or tungsten, or anitride film of any of these metals (a titanium nitride film, amolybdenum nitride film, or a tungsten nitride film) is stacked eitheror both of over and under a metal film of aluminum, copper, or the like.For example, a three layer structure consisting of a titanium film, analuminum film or a copper film, and a titanium film is preferablyemployed.

The gate insulating layer is formed using a material which transmitslight from the light-emitting element. The gate insulating layer can beformed to have a single-layer structure or a stacked-layer structureusing any of silicon oxide, silicon nitride, silicon oxynitride, siliconnitride oxide, and aluminum oxide by a plasma-enhanced CVD method, asputtering method, or the like, for example.

The semiconductor layer can be formed using a silicon semiconductor oran oxide semiconductor. As examples of the silicon semiconductor, singlecrystal silicon, polycrystalline silicon, and the like can be given. Asthe oxide semiconductor, an In—Ga—Zn-based metal oxide or the like canbe used as appropriate. The semiconductor layer is preferably formedusing an In—Ga—Zn-based metal oxide that is an oxide semiconductor suchthat the semiconductor layer is a semiconductor layer whose off-statecurrent is small, because the off-state leakage current of thelight-emitting element 130 can be reduced.

As the source electrode layer and the drain electrode layer, forexample, a metal film containing an element selected from aluminum,chromium, copper, tantalum, titanium, molybdenum, and tungsten; a metalnitride film containing any of the above elements (e.g., a titaniumnitride film, a molybdenum nitride film, or a tungsten nitride film); orthe like can be used. A structure may also be used in which a film of ahigh-melting-point metal such as titanium, molybdenum, or tungsten, or anitride film of any of these metals (a titanium nitride film, amolybdenum nitride film, or a tungsten nitride film) is stacked oneither or both of over and under a metal film of aluminum, copper, orthe like. For example, a three-layer structure consisting of a titaniumfilm, an aluminum film or a copper film, and a titanium film ispreferably used.

Further or alternatively, the source electrode layer and the drainelectrode layer may be formed using a conductive metal oxide. As theconductive metal oxide, indium oxide (In₂O₃ or the like), tin oxide(SnO₂ or the like), zinc oxide (ZnO), ITO, indium oxide-zinc oxide(In₂O₃—ZnO or the like), or any of these metal oxide materials in whichsilicon oxide is contained can be used.

[First Insulating Layer 114, Second Insulating Layer 116]

The first insulating layer 114 and a second insulating layer 116 areformed using materials which transmit light from the light-emittingelement.

The first insulating layer 114 has an effect of preventing diffusion ofimpurities into the semiconductor included in the transistor. As thefirst insulating layer 114, an inorganic insulating film such as asilicon oxide film, a silicon oxynitride film, or an aluminum oxide filmcan be used.

As the second insulating layer 116, an insulating film with aplanarization function is preferably selected in order to reduce surfaceunevenness due to a color filter or the transistor. For example, anorganic material such as a polyimide resin, an acrylic resin, or abenzocyclobutene resin can be used. Other than such organic materials,it is also possible to use a low-dielectric constant material (a low-kmaterial) or the like. The second insulating layer 116 may be foi Hiedby stacking a plurality of insulating films formed using any of thesematerials.

[Color Filter 166, Black Matrix 164]

For the sealing substrate 806, a color filter 166 that is a coloringlayer is provided to overlap with (the light-emitting region of) thelight-emitting element 130. The color filter 166 is provided in order tocontrol the color of light emitted from the light-emitting element 130.For example, in a full-color display device using white light-emittingelements, a plurality of light-emitting units provided with colorfilters of different colors are used. In that case, three colors, red(R), green (G), and blue (B), may be used, or four colors, red (R),green (G), blue (B), and yellow (Y), may be used.

Further, a black matrix 164 is provided between the adjacent colorfilters 166 (not to overlap with the light-emitting region of thelight-emitting element 130). The black matrix 164 shields thelight-emitting unit from light emitted from the light-emitting element130 in its adjacent light-emitting unit and thereby prevents colormixture between the adjacent light-emitting units. Here, the colorfilter 166 is provided so that its end portion overlaps with the blackmatrix 164, whereby light leakage can be suppressed. The black matrix164 can be formed using a material which shields light emitted from thelight-emitting element 130, for example, metal or resin. The blackmatrix 164 may be provided in a region other than the light-emittingportion 802, such as the driver circuit portion 803.

Further, an overcoat layer 168 is formed to cover the color filter 166and the black matrix 164. The overcoat layer 168 is formed using amaterial which transmits light emitted from the light-emitting element130; for example, an inorganic insulating film or an organic insulatingfilm can be used. The overcoat layer 168 is not necessarily providedunless needed.

In this embodiment, a light-emitting device using a color filter methodis described as an example; however, embodiments of the presentinvention are not limited thereto. For example, a separate coloringmethod or a color conversion method may be used.

This embodiment can be combined with any other embodiment asappropriate.

(Embodiment 5)

In this embodiment, structural examples of an EL layer applicable to alight-emitting device of one embodiment of the present invention aredescribed using FIGS. 6A to 6C.

A known substance can be used for the EL layer; either a low molecularcompound or a high molecular compound can be used. The constituentsubstance of the EL layer is not limited to an organic compound; aninorganic compound may be contained.

In FIG. 6A, an EL layer 120 is provided between a first electrode 118and a second electrode 122. In the EL layer 120 in FIG. 6A, ahole-injection layer 701, a hole-transport layer 702, a light-emittinglayer 703, an electron-transport layer 704, and an electron-injectionlayer 705 are stacked in this order from the first electrode 118 side.

A plurality of EL layers may be stacked between the first electrode 118and the second electrode 122 as shown in FIG. 6B. In that case, a chargegeneration layer 709 is preferably provided between a first EL layer 120a and a second EL layer 120 b which are stacked. In a light-emittingelement having such a structure, problems such as energy transfer andquenching less occur, which enables expansion in the choice ofmaterials, thereby achieving a light-emitting element which has bothhigh light emission efficiency and long lifetime easily. Moreover,phosphorescence and fluorescence can be obtained easily from one ELlayer and the other EL layer, respectively. This structure can becombined with the above-described EL layer structure.

Further, by forming EL layers to emit light of different colors fromeach other, a light-emitting element can provide light emission of adesired color as a whole. For example, by forming a light-emittingelement having two EL layers such that the emission color of the firstEL layer and the emission color of the second EL layer are colorscomplementary to each other, the light-emitting element can providewhite light emission as a whole. The “colors complementary to eachother” means colors which become an achromatic color by mixture of them.That is, once respective light emitted from substances whose emissioncolors are complementary to each other is mixed together, white emissioncolor can be obtained. This applies to a light-emitting element havingthree or more EL layers.

As shown in FIG. 6C, the EL layer 120 may include the hole-injectionlayer 701, the hole-transport layer 702, the light-emitting layer 703,the electron-transport layer 704, an electron-injection buffer layer706, an electron-relay layer 707, and a composite material layer 708which is in contact with the second electrode 122, between the firstelectrode 118 and the second electrode 122.

It is preferable to provide the composite material layer 708 which is incontact with the second electrode 122, because damage on the EL layer120 particularly in formation of the second electrode 122 by asputtering method can be attenuated.

Further, by the electron-injection buffer layer 706, an injectionbarrier between the composite material layer 708 and theelectron-transport layer 704 can be reduced; thus, electrons generatedin the composite material layer 708 can be easily injected to theelectron-transport layer 704.

Furthermore, the electron-relay layer 707 is preferably formed betweenthe electron-injection buffer layer 706 and the composite material layer708. The electron-relay layer 707 is not necessarily provided; however,the electron-relay layer 707 having a high electron-transport propertyenables electrons to be rapidly transported to the electron-injectionbuffer layer 706.

The structure in which the electron-relay layer 707 is sandwichedbetween the composite material layer 708 and the electron-injectionbuffer layer 706 is a structure in which the acceptor substancecontained in the composite material layer 708 and the donor substancecontained in the electron-injection buffer layer 706 are less likely tointeract with each other, and thus their functions hardly interfere witheach other. Accordingly, an increase in drive voltage can be suppressed.

Examples of respective materials which can be used for the layers aredescribed below. Each layer is not limited to a single layer, but may bea stack of two or more layers.

<Hole-Injection Layer 701>

The hole-injection layer 701 is a layer containing a substance having ahigh hole-injection property.

As the substance having a high hole-injection property, for example, ametal oxide such as molybdenum oxide, vanadium oxide, ruthenium oxide,tungsten oxide, or manganese oxide, a phthalocyanine-based compound suchas phthalocyanine (H₂Pc) and copper phthalocyanine (CuPc), or the likecan be used.

Further, a high molecular compound such as poly(N-vinylcarbazole)(abbreviation: PVK) or poly(4-vinyltriphenylamine) (abbreviation:PVTPA), or a high molecular compound to which acid is added, such aspoly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT/PSS)can also be used.

In particular, for the hole-injection layer 701, a composite materialcontaining an organic compound having a high hole-transport property andan electron acceptor (acceptor) is preferably used. Such a compositematerial has an excellent hole-injection and hole-transport propertiesbecause holes are generated in the organic compound by the electronacceptor. Such a composite material enables the hole-transportcapability from the first electrode 118 to the EL layer 120 to beincreased, whereby the drive voltage of the light-emitting element canbe decreased.

Such a composite material can be formed by co-evaporation of an organiccompound having a high hole-transport property and an electron acceptor.The hole-injection layer 701 is not limited to a structure in which anorganic compound having a high hole-transport property and an electronacceptor are contained in the same film, but may be a structure in whicha layer containing an organic compound having a high hole-transportproperty and a layer containing an electron acceptor are stacked.Specifically, a layer containing an electron acceptor is in contact withthe first electrode 118.

The organic compound used in the composite material is an organiccompound whose hole-transport property is higher than itselectron-transport property; particularly, it is preferable that thehole mobility of the organic compound be greater than or equal to 10⁻⁶cm²/Vs. As the organic compound for the composite material, any of avariety of compounds including, an aromatic amine compound, a carbazolederivative, an aromatic hydrocarbon compound, and a high molecularcompound can be used.

As examples of the aromatic amine compound,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB orα-NPD), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation:BPAFLP), and the like can be given.

As examples of the carbazole derivative, 4,4′-di(N-carbazolyl)biphenyl(abbreviation: CBP), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole(abbreviation: CzPA),9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation:PCzPA), and the like can be given.

As examples of the aromatic hydrocarbon compound,2-tert-butyl-9,10-di(2-naphthyl)anthracene (abbreviation: t-BuDNA),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),9,10-diphenylanthracene (abbreviation: DPAnth), and the like can begiven.

As examples of the high molecular compound, PVK, PVTPA, and the like canbe given.

As examples of the electron acceptor for the composite material, atransition metal oxide or an oxide of a metal belonging to Group 4 toGroup 8 of the periodic table can be given. Specifically, molybdenumoxide is preferable. Molybdenum oxide is easy to handle because of itsstability in the air and its low hygroscopic property.

<Hole-Transport Layer 702>

The hole-transport layer 702 is a layer which contains a substancehaving a high hole-transport property.

The substance having a high hole-transport property is a substance whosehole-transport property is higher than its electron-transport property;particularly, it is preferable that the hole mobility of the substancehaving a high hole-transport property be greater than or equal to 10⁻⁶cm²/Vs. For example, any of a variety of compounds such as an aromaticamine compound such as NPB or BPAFLP, a carbazole derivative such asCBP, CzPA, or PCzPA, an aromatic hydrocarbon compound such as t-BuDNA,DNA, or DPAnth, and a high molecular compound such as PVK or PVTPA canbe used.

<Light-Emitting Layer 703>

For the light-emitting layer 703, a fluorescent compound that exhibitsfluorescence or a phosphorescent compound that exhibits phosphorescencecan be used.

As examples of the fluorescent compound for the light-emitting layer703,N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine(abbreviation: YGA2S),N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: 2PCAPA), rubrene, and the like can be given.

As examples of the phosphorescent compound for the light-emitting layer703, metallo-organic complexes such asbis[2-(4′,6′-difluorophenyl)pyridinato-N,C^(2′)]iridium(III)picolinate(abbreviation: FIrpic), tris(2-phenylpyridinato-N,C^(2′))iridium(III)(abbreviation: Ir(ppy)₃), and(acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III)(abbreviation: Ir(mppr-Me)₂(acac)) can be given.

The light-emitting layer 703 may have a structure in which any of theabove-described light-emitting organic compounds (a light-emittingsubstance or a guest material) is dispersed in another substance (a hostmaterial). As the host material, any of a variety of materials can beused, and it is preferable to use a substance which has a lowestunoccupied molecular orbital level (LUMO level) higher than that of theguest material and has a highest occupied molecular orbital level (HOMOlevel) lower than that of the guest material.

With a structure in which a guest material is dispersed in a hostmaterial, crystallization of the light-emitting layer 703 can besuppressed. Further, concentration quenching due to high concentrationof the guest material can be suppressed.

As the host material, specifically, a metal complex such astris(8-quinolinolato)aluminum(III) (abbreviation: Alq) orbis(2-methyl-8-quinolinolato) (4-phenylphenolato)aluminum(III)(abbreviation: BAlq), a heterocyclic compound such as3-(4′-tert-butylphenyl)-4-phenyl-5-(4″-biphenyl)-1,2,4-triazole(abbreviation: TAZ), bathophenanthroline (abbreviation: BPhen), orbathocuproine (abbreviation: BCP), a condensed aromatic compound such asCzPA, DNA, t-BuDNA, or DPAnth, an aromatic amine compound such as NPB,or the like can be used.

Plural kinds of materials can be used for the host material. Forexample, to suppress crystallization, a substance such as rubrene whichsuppresses crystallization, may be further added. In addition, NPB, Alq,or the like may be further added in order to efficiently transfer energyto the guest material.

Further, by providing a plurality of light-emitting layers such thattheir respective emission colors are different from each other, lightemission of a desired color can be obtained from the light-emittingelement as a whole. For example, by using first and secondlight-emitting layers whose emission colors are complementary to eachother in a light-emitting element having the two light-emitting layers,the light-emitting element can be made to emit white light as a whole.The same applies to a light-emitting element having three or morelight-emitting layers.

<Electron-Transport Layer 704>

The electron-transport layer 704 is a layer which contains a substancehaving a high electron-transport property.

The substance having a high electron-transport property is an organiccompound whose electron-transport property is higher than itshole-transport property; particularly, it is preferable that theelectron mobility of the substance having a high electron-transportproperty be greater than or equal to 10⁻⁶ cm²/vs.

As the substance having a high electron-transport property, a metalcomplex having a quinoline skeleton or a benzoquinoline skeleton, suchas Alq or BAlq, a metal complex having an oxazole-based orthiazole-based ligand, such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc(abbreviation: Zn(BOX)₂) or bis[2-(2-hydroxyphenyl)-benzothiazolato]zinc(abbreviation: Zn(BTZ)₂), or the like can be used. Further, TAZ, BPhen,BCP, or the like can also be used.

<Electron-Injection Layer 705>

The electron-injection layer 705 is a layer which contains a substancehaving a high electron-injection property.

As the substance having a high electron-injection property, an alkalimetal such as lithium, an alkaline earth metal such as cesium orcalcium, or a compound thereof such as lithium fluoride, cesiumfluoride, calcium fluoride, or lithium oxide can be used. Further, arare earth metal compound such as erbium fluoride can also be used. Anyof the above-described substances for the electron-transport layer 704can also be used.

The hole-injection layer 701, the hole-transport layer 702, thelight-emitting layer 703, the electron-transport layer 704, and theelectron-injection layer 705 which are described above can each beformed by an evaporation method (e.g., a vacuum evaporation method), anink-jet method, a coating method, or the like.

<Charge Generation Layer 709>

The charge generation layer 709 shown in FIG. 6B can be formed using theabove-described composite material. The charge generation layer 709 mayhave a stacked-layer structure including a layer containing thecomposite material and a layer containing another material. In thatcase, as the layer containing another material, a layer containing anelectron donating substance and a substance having a highelectron-transport property, a layer formed of a transparent conductivefilm, or the like can be used.

<Composite Material Layer 708>

For the composite material layer 708 shown in FIG. 6C, theabove-described composite material containing an organic compound havinga high hole-transport property and an electron acceptor can be used.

<Electron-Injection Buffer Layer 706>

For the electron-injection buffer layer 706, a substance having a highelectron-injection property, such as an alkali metal, an alkaline earthmetal, a rare earth metal, or a compound of any of the above metals(including an oxide such as lithium oxide, a halide, and a carbonatesuch as lithium carbonate or cesium carbonate) can be used.

Further, in the case where the electron-injection buffer layer 706contains a substance having a high electron-transport property and adonor substance, the donor substance is preferably added so that themass ratio of the donor substance to the substance having a highelectron-transport property is from 0.001:1 to 0.1:1. As the donorsubstance, an organic compound such as tetrathianaphthacene(abbreviation: TTN), nickelocene, or decamethylnickelocene can be usedas well as an alkali metal, an alkaline earth metal, a rare earth metal,or a compound of any of the above metals. As the substance having a highelectron-injection property, a material similar to any of theabove-described materials for the electron-transport layer 704 can beused.

<Electron-Relay Layer 707>

The electron-relay layer 707 contains a substance having a highelectron-transport property and is formed so that the LUMO level of thesubstance having a high electron-transport property is located betweenthe LUMO level of the acceptor substance contained in the compositematerial layer 708 and the LUMO level of the substance having a highelectron-transport property contained in the electron-transport layer704. In the case where the electron-relay layer 707 contains a donorsubstance, the donor level of the donor substance is adjusted so as tobe located between the LUMO level of the acceptor material contained inthe composite material layer 708 and the LUMO level of the substancehaving a high electron-transport property contained in theelectron-transport layer 704. As for the specific value of the energylevel, the LUMO level of the substance having a high electron-transportproperty contained in the electron-relay layer 707 is preferably greaterthan or equal to −5.0 eV, more preferably greater than or equal to −5.0eV and less than or equal to −3.0 eV.

As the substance having a high electron-transport property contained inthe electron-relay layer 707, a phthalocyanine-based material or a metalcomplex having a metal-oxygen bond and an aromatic ligand is preferablyused.

As examples of the phthalocyanine-based material for the electron-relaylayer 707, specifically, CuPc, PhO-VOPc (Vanadyl2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine), and the like can begiven.

As the metal complex having a metal-oxygen bond and an aromatic ligandfor the electron-relay layer 707, a metal complex having a metal-oxygendouble bond is preferably used. The metal-oxygen double bond has anacceptor property (properties of high electron acceptability), whichfacilitate transfer (donation and acceptance) of electrons.

As the metal complex having a metal-oxygen bond and an aromatic ligand,a phthalocyanine-based material is preferable. In particular, a materialin which a metal-oxygen double bond is more likely to act on anothermolecular in terms of a molecular structure and having a high acceptorproperty is preferable.

As the phthalocyanine-based material, a phthalocyanine-based materialhaving a phenoxy group is preferable. Specifically, a phthalocyaninederivative having a phenoxy group, such as PhO-VOPc, is preferable. Thephthalocyanine derivative having a phenoxy group is soluble in asolvent, and thus has a merit of easy handling for formation of alight-emitting element. In addition, the phthalocyanine derivativehaving a phenoxy group, which is soluble in a solvent, also has a meritof easy maintenance of an apparatus for forming a film thereof.

The electron-relay layer 707 may contain a donor substance. As examplesof the donor substance, materials similar to the donor materials for theelectron-injection buffer layer 706 can be given. The donor substancecontained in the electron-relay layer 707 facilitates electron transfer,enabling the drive voltage of the light-emitting element to bedecreased.

In the case where the donor substance is contained in the electron-relaylayer 707, as for the substance having a high electron-transportproperty, a substance having a LUMO level higher than the acceptor levelof the acceptor substance contained in the composite material layer 708can be used as well as the materials described above. As for thespecific energy level, the LUMO level is preferably greater than orequal to −5.0 eV, more preferably greater than or equal to −5.0 eV andless than or equal to −3.0 eV. As examples of such a material, aperylene derivative such as 3,4,9,10-perylenetetracarboxylic dianhydride(abbreviation: PTCDA), a nitrogen-containing condensed aromatic compoundsuch as pirazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile(abbreviation: PPDN), and the like can be given. The nitrogen-containingcondensed aromatic compound is preferable for the electron-relay layer707 because of its stability.

Through the above, the EL layer of this embodiment can be formed.

This embodiment can be combined with any other embodiment asappropriate.

(Embodiment 6)

In this embodiment, using FIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C,description is given of examples of a variety of electronic devices andlighting devices to each of which a light-emitting device of oneembodiment of the present invention can be applied.

In the light-emitting device of one embodiment of the present invention,the adhesion between the substrate and the glass layer in a cornerportion of the light-emitting device is high; therefore, if force isconcentrated on the corner portion of the light-emitting device, thepair of attached substrates is less likely to be detached from eachother. Thus, highly reliable electronic device and highly reliablelighting device can be achieved by application of the light-emittingdevice of one embodiment of the present invention.

Examples of the electronic devices to which the light-emitting device isapplied are television devices (also referred to as TV or televisionreceivers), monitors for computers and the like, cameras such as digitalcameras and digital video cameras, digital photo frames, mobile phones(also referred to as portable telephone devices), portable gamemachines, portable information terminals, audio playback devices, largegame machines such as pin-ball machines, and the like. Specific examplesof these electronic devices and the lighting device are illustrated inFIGS. 7A to 7E, FIG. 8, and FIGS. 9A to 9C.

FIG. 7A illustrates an example of a television device. In a televisiondevice 7100, a display portion 7103 is incorporated in a housing 7101.Images can be displayed on the display portion 7103 to which thelight-emitting device of one embodiment of the present invention can beapplied. Application of the light-emitting device of one embodiment ofthe present invention to the display portion 7103 enables achievement ofa highly reliable television device. In FIG. 7A, the housing 7101 issupported by a stand 7105.

The television device 7100 can be operated by an operation switch of thehousing 7101 or a separate remote controller 7110. With operation keys7109 of the remote controller 7110, channels and volume can becontrolled to control images displayed on the display portion 7103. Theremote controller 7110 may be provided with a display portion 7107 onwhich data output from the remote controller 7110 is displayed.

The television device 7100 is provided with a receiver, a modem, or thelike. With the receiver, a general television broadcast can be received.Furthermore, the television device 7100 can be connected to acommunication network by wired or wireless connection via the modem,which enables one-way (from a transmitter to a receiver) or two-way(between a transmitter and a receiver, between receivers, or the like)data communication.

FIG. 7B illustrates a computer, which includes a main body 7201, a bezel7202, a display portion 7203, a keyboard 7204, an external connectionport 7205, a pointing device 7206, and the like. The light-emittingdevice of one embodiment of the present invention is applied to thedisplay portion 7203 in this computer. Application of the light-emittingdevice of one embodiment of the present invention to the display portion7203 enables achievement of a highly reliable computer.

FIG. 7C illustrates a portable game machine, which includes twohousings, a housing 7301 and a housing 7302, which are connected with ajoint portion 7303 so that the portable game machine can be opened andfolded. A display portion 7304 is incorporated in the housing 7301 and adisplay portion 7305 is incorporated in the housing 7302. In addition,the portable game machine iilustrated in FIG. 7C has a speaker portion7306, a recording medium insertion portion 7307, an LED lamp 7308, aninput means (an operation key 7309, a connection terminal 7310, a sensor7311 (a sensor of measuring force, displacement, position, speed,acceleration, angular velocity, rotational frequency, distance, light,liquid, magnetism, temperature, chemical substance, sound, time,hardness, electric field, current, voltage, electric power, radiation,flow rate, humidity, gradient, oscillation, odor, or infrared rays), anda microphone 7312), and the like. Needless to say, the structure of theportable game machine is not limited to the above as long as thelight-emitting device of, one embodiment of the present invention isused for at least either one or both of the display portion 7304 and thedisplay portion 7305, and can have any other accessory as appropriate.Application of the light-emitting device of one embodiment of thepresent invention to the display portion 7304 and/or the display portion7305 enables achievement of a highly reliable portable game machine. Theportable game machine illustrated in FIG. 7C has a function of readingout a program or data stored in a storage medium to display it on thedisplay portion, or a function of sharing information with anotherportable game machine by wireless communication. The portable gamemachine illustrated in FIG. 7C can have a variety of functions withoutlimitation to the above.

FIG. 7D illustrates an example of a mobile phone. A mobile phone 7400has a display portion 7402 incorporated in a housing 7401, operationbuttons 7403, an external connection port 7404, a speaker 7405, amicrophone 7406, and the like. The light-emitting device of oneembodiment of the present invention is applied to the display portion7402 in the mobile phone 7400. Application of the light-emitting deviceof one embodiment of the present invention to the display portion 7402enables achievement of a highly reliable mobile phone.

Through a touch on the display portion 7402 of the mobile phone 7400illustrated in FIG. 7D with a finger or the like, data can be input intothe mobile phone 7400. Further, operations such as making a call andcreating e-mail can be performed by a touch on the display portion 7402with a finger or the like.

There are mainly three screen modes of the display portion 7402. Thefirst mode is a display mode mainly for displaying images. The secondmode is an input mode mainly for inputting data such as text. The thirdmode is a display-and-input mode in which two modes of the display modeand the input mode are combined.

For example, in the case of making a call or creating an e-mail, thetext input mode mainly for inputting text is selected for the displayportion 7402 so that text displayed on its screen can be input. In thiscase, it is preferable to display a keyboard or number buttons on almostthe entire screen of the display portion 7402.

Further, a detection device including a sensor for detectinginclination, such as a gyroscope or an acceleration sensor, is providedinside the mobile phone 7400, with which display on the screen of thedisplay portion 7402 can be automatically changed in response to thedetermined orientation of the mobile phone 7400 (whether the mobilephone is placed horizontally or vertically for a landscape mode or aportrait mode).

The screen mode is switched by touching the display portion 7402 oroperating the operation button 7403 of the housing 7401. The screen modecan also be switched depending on the kind of image displayed on thedisplay portion 7402. For example, when the signal of an image displayedon the display portion is a signal of moving image data, the screen modeis switched to the display mode, whereas when the signal is a signal oftext data, the screen mode is switched to the input mode.

Moreover, in the input mode, a signal detected by an optical sensor inthe display portion 7402 can be detected, whereby the screen mode may becontrolled so as to be switched from the input mode to the display modein the case where input by touching the display portion 7402 is notperformed for a specified period.

The display portion 7402 may function as an image sensor. For example,an image of a palm print, a fingerprint, or the like is taken by touchon the display portion 7402 with the palm or finger, whereby personalauthentication can be performed. Further, by using a backlight or asensing light source which emits a near-infrared light in the displayportion, an image of a finger vein, a palm vein, or the like can betaken.

FIG. 7E illustrates a desk lamp including a lighting portion 7501, ashade 7502, an adjustable arm 7503, a support 7504, a base 7505, and apower supply 7506. The light-emitting device of one embodiment of thepresent invention is applied to the lighting portion 7501 of the desklamp. Application of the light-emitting device of one embodiment of thepresent invention to the lighting portion 7501 enables achievement of ahighly reliable desk lamp. The lamp includes a ceiling light, a walllight, and the like in its category.

FIG. 8 illustrates an example in which the light-emitting device of oneembodiment of the present invention is applied to an indoor lightingdevice 811. The area of the light-emitting device of one embodiment ofthe present invention can be scaled up, which enables application to alarge-area lighting device. Furthermore, the light-emitting device canbe used as a roll-type lighting device 812. As illustrated in FIG. 8, adesk lamp 813, which is described in FIG. 7E, may also be used in a roomprovided with the interior lighting device 811.

FIGS. 9A and 9B illustrate a foldable tablet terminal. In FIG. 9A, thetablet terminal is opened, and includes a housing 9630, a displayportion 9631 a, a display portion 9631 b, a display-mode switchingbutton 9034, a power button 9035, a power-saving-mode switching button9036, a clip 9033, and an operation button 9038.

Part of the display portion 9631 a can form a touch panel region 9632 a,in which data can be input by touching operation keys 9037 which aredisplayed. Although a structure in which a half region in the displayportion 9631 a has only a display function and the other half region hasa touch panel function is shown as an example in FIG. 9A, the displayportion 9631 a is not limited to this structure. The entire area of thedisplay portion 9631 a may have a touch panel function. For example,keyboard buttons are displayed on the entire screen of the displayportion 9631 a such that the entire screen of the display portion 9631 afunctions as a touch panel, whereas the display portion 9631 b can beused as a display screen.

Like the display portion 9631 a, part of the display portion 9631 b canform a touch panel region 9632 b. Further, a switching button 9639 forshowing/hiding a keyboard of the touch panel can be touched with afinger, a stylus, or the like, so that keyboard buttons can be displayedon the display portion 9631 b.

Touch input can be performed concurrently on the touch panel regions9632 a and 9632 b.

The display-mode switching button 9034 can switch the displayorientation (e.g., between landscape mode and portrait mode) and selecta display mode (switch between monochrome display and color display),for example. With the power-saving-mode switching button 9036, theluminance of display can be optimized in accordance with the amount ofexternal light when the tablet is in use, which is detected with anoptical sensor incorporated in the tablet. The tablet may include anyanother detection device such as a sensor for detecting orientation(e.g., a gyroscope or an acceleration sensor) as well as the opticalsensor.

FIG. 9A illustrates an example in which the display portion 9631 a andthe display portion 9631 b have the same display area; however, withoutlimitation thereon, one of the display portions may be different fromthe other display portion in size or display quality. For example, oneof them may be a display panel that can display higher-definition imagesthan the other.

In FIG. 9B, the tablet terminal is folded, which includes the housing9630, a solar battery 9633, a charge and discharge control circuit 9634,a battery 9635, and a DCDC converter 9636. FIG. 9B illustrates anexample in which the charge and discharge control circuit 9634 includesthe battery 9635 and the DCDC converter 9636.

Since the tablet terminal can be folded in two, the housing 9630 can beclosed when the tablet is not in use. Thus, the display portions 9631 aand 9631 b can be protected, thereby providing a tablet terminal withhigh endurance and high reliability for long-term use.

In addition, the tablet terminal illustrated in FIGS. 9A and 9B can havea function of displaying a variety of data (e.g., a still image, amoving image, and a text image), a function of displaying a calendar, adate, the time, or the like on the display portion, a touch-inputfunction of operating or editing the data displayed on the displayportion by touch input, a function of controlling processing by avariety of software (programs), and the like.

The solar battery 9633, which is attached on the surface of the tabletterminal, supplies electric power to a touch panel, a display portion,an image signal processor, and the like. The solar cell 9633 ispreferably provided on one or two surfaces of the housing 9630, becausethe battery 9635 can be charged efficiently. A lithium ion battery canbe used as the battery 9635, which has a merit in reduction in size orthe like.

The structure and the operation of the charge and discharge controlcircuit 9634 illustrated in FIG. 9B are described using a block diagramin FIG. 9C. FIG. 9C illustrates the solar battery 9633, the battery9635, the DCDC converter 9636, a converter 9637, switches SW1 to SW3,and the display portion 9631. The battery 9635, the DCDC converter 9636,the converter 9637, and the switches SW1 to SW3 are included in thecharge and discharge control circuit 9634 in FIG. 9B.

First, an example of operation in the case where power is generated bythe solar battery 9633 using external light is described. The voltage ofpower generated by the solar battery is raised or lowered by the DCDCconverter 9636 to a voltage for charging the battery 9635. Then, whenthe power from the solar battery 9633 is used for the operation of thedisplay portion 9631, the switch SW1 is turned on and the voltage of thepower is raised or lowered by the converter 9637 to a voltage needed forthe display portion 9631. On the other hand, when display on the displayportion 9631 is not performed, the switch SW1 is turned off and theswitch SW2 is turned on so that the battery 9635 is charged.

In this embodiment, the solar battery 9633 is described as an example ofa power generation means; however, there is no particular limitation ona way of charging the battery 9635, and the battery 9635 may be chargedwith another power generation means such as a piezoelectric element or athermoelectric conversion element (Peltier element). For example, thebattery 9635 may be charged with a non-contact power transmission modulewhich is capable of charging by transmitting and receiving power bywireless (without contact), or another charging means may be used incombination.

As described above, electronic devices and lighting devices can beobtained by application of the light-emitting device of one embodimentof the present invention. The applicable range of the light-emittingdevice of one embodiment of the present invention is so wide that thelight-emitting device can be applied to electronic devices in any field.

The structure described in this embodiment can be combined with anystructure described in any of the above embodiments as appropriate.

EXAMPLE 1

In this example, a sealed structure of one embodiment of the presentinvention is described using FIGS. 10A to 10C, FIGS. 11A and 11B, andFIGS. 12A and 12B.

First, a method for manufacturing a sealed structure of this example isdescribed using FIGS. 10A to 10C. In each of FIGS. 10A to 10C, a planview and a cross-sectional view taken along dashed-dotted line G-H inthe plan view are shown. A glass substrate 209 is omitted in the planviews of FIGS. 10B and 10C.

As shown in FIG. 10A, frit paste 203 was applied over a glass substrate201 by screen printing. A glass paste containing bismuth oxide or thelike was used as the frit paste 203.

Then, drying was performed thereon at 140° C. for 20 minutes.

Images of the frit paste 203 applied over the glass substrate 201, withan optical microscope are shown in FIGS. 11A and 11B. FIG. 11A is theimage of a region surrounded by a dotted line 211 in FIG. 10A, and FIG.11B is the image of a region surrounded by a dotted line 213 in FIG.10A. As seen from FIGS. 11A and 11B, the width of a corner portion ofthe frit paste 203 is larger than that of a side portion of the fritpaste 203. Further, in the corner portion, the radius of the outercontour is smaller than that of the inner contour.

Next, pre-baking was performed thereon to remove an organic solvent or aresin in the frit paste 203. In this manner, a glass layer 204 wasformed. As the pre-baking, drying was performed at 450° C. for 60minutes.

Then, the glass substrate 201 and the glass substrate 209 were disposedto face each other to make the glass layer 204 and the glass substrate209 in close contact with each other, and the glass layer 204 wasirradiated with laser light 207 from the glass substrate 201 side (seeFIG. 10B). The laser light irradiation was performed under the followingconditions: a semiconductor laser with a wavelength of 940 nm was used,the output power was 28 W, and the scanning speed was 1 mm/sec. The beamdiameter of the laser beam 207 was greater than the width of a cornerportion of the glass layer 204.

Through the above, the sealed structure of this example in which theglass substrate 201 is attached to the glass substrate 209 with a glasslayer 205 was manufactured (FIG. 10C).

Images of a welded region between the glass layer 205 and the glasssubstrate 209 of the sealed structure of this example, with an opticalmicroscope are shown in FIGS. 12A and 12B. Specifically, the weldedregion was observed in a direction denoted by an arrow 215 in FIG. 10C.

FIG. 12A shows a part of the welded region surrounded by a dotted line217 in FIG. 10C, and FIG. 12B is a part of the welded region surroundedby a dotted line 219 in FIG. 10C.

As seen from FIGS. 11A and 11B and FIGS. 12A and 12B, a differencebetween the shape of the frit paste 203 (FIGS. 11A and 11B) and theshape of the glass layer 205 (FIGS. 12A and 12B) is small. That is, itis found that a change of shape of the glass layer 205 between beforeand after the attachment is small. Therefore, a sealed structure can bemanufactured at a yield higher than that in the case where a resin isused.

As shown in FIGS. 12A and 12B, the width of a corner portion of thewelded region between the glass layer 205 and the glass substrate 209 islarger than that of a side portion of the welded region. Further, in thecorner portion, the radius of the outer contour is smaller than that ofthe inner contour.

The area of the welded region between the glass layer and the substratein a corner portion of the sealed structure manufactured in this exampleis large. Accordingly, according to one embodiment of the presentinvention, the sealed structure with high adhesion between the glasslayer and the substrate in its corner portion can be provided.

This application is based on Japanese Patent Application serial no.2011-260216 filed with Japan Patent Office on Nov. 29, 2011, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A sealed structure comprising: a first substrateand a second substrate, a first surface of the first substrate facing afirst surface of the second substrate; and a glass layer which is incontact with the first substrate and the second substrate, defines asealed space between the first substrate and the second substrate, andis provided along a periphery of the first surface of the firstsubstrate, wherein the glass layer is seamlessly provided along theperiphery of the first surface of the first substrate, wherein the glasslayer comprises a welded region, wherein the first substrate and thewelded region each include a corner portion and a side portion, whereinan area of the first surface of the first substrate is smaller than orequal to an area of the first surface of the second substrate, andwherein a width of the corner portion of the welded region is largerthan a width of the side portion of the welded region.
 2. The sealedstructure according to claim 1, wherein at least one of the firstsubstrate and the second substrate comprises a film formed over thefirst surface thereof.
 3. A sealed structure comprising: a firstsubstrate and a second substrate, a first surface of the first substratefacing a first surface of the second substrate; and a glass layer whichis in contact with the first substrate and the second substrate, definesa sealed space between the first substrate and the second substrate, andis provided along a periphery of the first surface of the firstsubstrate, wherein the glass layer is seamlessly provided along theperiphery of the first surface of the first substrate, wherein the glasslayer comprises a welded region, wherein the first substrate and thewelded region each include a corner portion, wherein an area of thefirst surface of the first substrate is smaller than or equal to an areaof the first surface of the second substrate, and wherein a radius of anouter contour of the corner portion of the welded region is smaller thanor equal to a radius of an inner contour of the corner portion of thewelded region.
 4. The sealed structure according to claim 3, wherein atleast one of the first substrate and the second substrate comprises afilm formed over the first surface thereof.
 5. A light-emitting devicecomprising: a first substrate and a second substrate, a first surface ofthe first substrate facing a first surface of the second substrate; anda glass layer which is in contact with the first substrate and thesecond substrate, defines a region for an object to be sealed betweenthe first substrate and the second substrate, and is provided along aperiphery of the first surface of the first substrate, wherein the glasslayer is seamlessly provided along the periphery of the first surface ofthe first substrate, wherein the glass layer comprises a welded region,wherein the first substrate and the welded region each include a cornerportion and a side portion, wherein an area of the first surface of thefirst substrate is smaller than or equal to an area of the first surfaceof the second substrate, wherein the region for the object to be sealedincludes a light-emitting element in which a layer containing alight-emitting organic compound is provided between a pair ofelectrodes, and wherein a width of the corner portion of the weldedregion is larger than a width of the side portion of the welded region.6. The light-emitting device according to claim 5, wherein at least oneof the first substrate and the second substrate comprises a film formedover the first surface thereof.
 7. An electronic device wherein thelight-emitting device according to claim 5 is used in a display portion.8. A lighting device wherein the light-emitting device according toclaim 5 is used in a light-emitting portion.
 9. A light-emitting devicecomprising: a first substrate and a second substrate, a first surface ofthe first substrate facing a first surface of the second substrate; anda glass layer which is in contact with the first substrate and thesecond substrate, defines a region for an object to be sealed betweenthe first substrate and the second substrate, and is provided along aperiphery of the first surface of the first substrate, wherein the glasslayer is seamlessly provided along the periphery of the first surface ofthe first substrate, wherein the glass layer comprises a welded region,wherein the first substrate and the welded region each include a cornerportion, wherein an area of the first surface of the first substrate issmaller than or equal to an area of the first surface of the secondsubstrate, wherein the region for the object to be sealed includes alight-emitting element in which a layer containing a light-emittingorganic compound is provided between a pair of electrodes, and wherein aradius of an outer contour of the corner portion of the welded region issmaller than or equal to a radius of an inner contour of the cornerportion of the welded region.
 10. The light-emitting device according toclaim 9, wherein at least one of the first substrate and the secondsubstrate comprises a film formed over the first surface thereof.
 11. Anelectronic device wherein the light-emitting device according to claim 9is used in a display portion.
 12. A lighting device wherein thelight-emitting device according to claim 9 is used in a light-emittingportion.
 13. The sealed structure according to claim 1, wherein theglass layer includes a glass material selected from magnesium oxide,calcium oxide, strontium oxide, barium oxide, cesium oxide, sodiumoxide, potassium oxide, boron oxide, vanadium oxide, zinc oxide,tellurium oxide, aluminum oxide, silicon dioxide, lead oxide, tin oxide,phosphorus oxide, ruthenium oxide, rhodium oxide, iron oxide, copperoxide, manganese dioxide, molybdenum oxide, niobium oxide, titaniumoxide, tungsten oxide, bismuth oxide, zirconium oxide, lithium oxide,antimony oxide, lead borate glass, tin phosphate glass, vanadate glass,and borosilicate glass.
 14. The sealed structure according to claim 3,wherein the glass layer includes a glass material selected frommagnesium oxide, calcium oxide, strontium oxide, barium oxide, cesiumoxide, sodium oxide, potassium oxide, boron oxide, vanadium oxide, zincoxide, tellurium oxide, aluminum oxide, silicon dioxide, lead oxide, tinoxide, phosphorus oxide, ruthenium oxide, rhodium oxide, iron oxide,copper oxide, manganese dioxide, molybdenum oxide, niobium oxide,titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide, lithiumoxide, antimony oxide, lead borate glass, tin phosphate glass, vanadateglass, and borosilicate glass.
 15. The light-emitting device accordingto claim 5, wherein the glass layer includes a glass material selectedfrom magnesium oxide, calcium oxide, strontium oxide, barium oxide,cesium oxide, sodium oxide, potassium oxide, boron oxide, vanadiumoxide, zinc oxide, tellurium oxide, aluminum oxide, silicon dioxide,lead oxide, tin oxide, phosphorus oxide, ruthenium oxide, rhodium oxide,iron oxide, copper oxide, manganese dioxide, molybdenum oxide, niobiumoxide, titanium oxide, tungsten oxide, bismuth oxide, zirconium oxide,lithium oxide, antimony oxide, lead borate glass, tin phosphate glass,vanadate glass, and borosilicate glass.
 16. The light-emitting deviceaccording to claim 9, wherein the glass layer includes a glass materialselected from magnesium oxide, calcium oxide, strontium oxide, bariumoxide, cesium oxide, sodium oxide, potassium oxide, boron oxide,vanadium oxide, zinc oxide, tellurium oxide, aluminum oxide, silicondioxide, lead oxide, tin oxide, phosphorus oxide, ruthenium oxide,rhodium oxide, iron oxide, copper oxide, manganese dioxide, molybdenumoxide, niobium oxide, titanium oxide, tungsten oxide, bismuth oxide,zirconium oxide, lithium oxide, antimony oxide, lead borate glass, tinphosphate glass, vanadate glass, and borosilicate glass.
 17. The sealedstructure according to claim 1, wherein the first substrate includes afirst portion and a second portion, wherein a thickness of the firstportion is larger than a thickness of the second portion, wherein thefirst portion is in contact with the glass layer, and wherein the secondportion is not in contact with the glass layer.
 18. The sealed structureaccording to claim 3, wherein the first substrate includes a firstportion and a second portion, wherein a thickness of the first portionis larger than a thickness of the second portion, wherein the firstportion is in contact with the glass layer, and wherein the secondportion is not in contact with the glass layer.
 19. The light-emittingdevice according to claim 5, wherein the first substrate includes afirst portion and a second portion, wherein a thickness of the firstportion is larger than a thickness of the second portion, wherein thefirst portion is in contact with the glass layer, and wherein the secondportion is not in contact with the glass layer.
 20. The light-emittingdevice according to claim 9, wherein the first substrate includes afirst portion and a second portion, wherein a thickness of the firstportion is larger than a thickness of the second portion, wherein thefirst portion is in contact with the glass layer, and wherein the secondportion is not in contact with the glass layer.